Monday, October 27, 2014

Apriori in JAVA

import java.util.*;
public class Apriori {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
Apriori x=new Apriori();
Vector<String> v=new Vector<String>(), temp=new Vector<String>(), prev=new Vector<String>();
System.out.println("Enter no. of items:");
int p=1, n=sc.nextInt();
System.out.println("Enter no. of transactions:");
int t=sc.nextInt();
String s[]=new String[t];
for(int i=0;i<t;i++)
{
System.out.print("Transaction "+(i+1)+": ");
s[i]=sc.next();
}
System.out.println("Enter value for minimum support: ");
int minSupp=sc.nextInt();
System.out.println("\nInitial count:\nItem\tCount");
for(int i=0;i<n;i++)
{
System.out.println((i+1)+"\t"+x.count(s, (i+1)+""));
if(x.count(s, (i+1)+"")>=minSupp)
v.add((i+1)+"");
temp.add(i+"");
}
System.out.println("\nFrequent "+(p++)+" itemsets: "+v);
do{
temp.removeAllElements();
prev.removeAllElements();
for(int i=0;i<v.size();i++)
prev.add(v.elementAt(i));
for(int i=0;i<v.size();i++)
for(int j=i+1;j<v.size();j++)
{
String str=v.elementAt(i)+v.elementAt(j);
if(x.count(s, str)>=minSupp)
temp.add(x.removeDuplicates(str));
}
v.removeAllElements();
for(int i=0;i<temp.size();i++)
v.add(temp.elementAt(i));
x.removeRepeated(v);
v = new Vector(new LinkedHashSet(v));
if(!v.isEmpty())
System.out.println("Frequent "+(p++)+" itemsets: "+v);
}while(!v.isEmpty());
}
int count(String[] a, String s)
{
int count=0;
for(int i=0;i<a.length;i++)
if(intersect(s, a[i]))
count++;
return count;
}
boolean intersect(String s1, String s2)
{
boolean b=true;
for(int i=0;i<s1.length();i++)
if(s2.indexOf(s1.charAt(i)+"")==-1)
{
b=false;
break;
}
return b;
}
String removeDuplicates(String s)
{
StringBuilder noDupes = new StringBuilder();
for (int i = 0; i < s.length(); i++)
{
String si = s.substring(i, i+1);
if (!si.equals(",") && noDupes.indexOf(si) == -1)
noDupes.append(si);
}
return noDupes.toString();
}
Vector<String> removeRepeated(Vector<String> vect)
{
for(int i=0;i<vect.size();i++)
{
char[] chars = vect.elementAt(i).toCharArray();
Arrays.sort(chars);
vect.removeElementAt(i);
vect.add(i, new String(chars));
}
return vect;
}
}

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